T2kdm

Changed
- Storage at TRIUMF is now marked as broken, since we no longer use it.

Removed
- Support for Python 2.x

Added
- Support for Python 3.x

Added
- Added `pre-commit` hooks.

Changed
- Official code style is now Black.

Fixed
- CLI now actually caches directory entries for quicker tab completion.

Added
- Added `IN2P3-CC-XRD-disk` and `IN2P3-CC-XRD-tape`.
- `check` will now check whether a file has no replicas at all.

Changed
- `UKI-SOUTHGRID-OX-HEP-disk` is marked as broken, since the SE will be switched off